namespace ConsoleApplication1
{
    
    public delegate void methodDelegate(string str);
    class Program
    {
        static void Main(string[] args)
        {
            Student student = new Student();
            Teacher teacher = new Teacher("王老师");
            methodDelegate methodDelegate1 = new methodDelegate(student.getStudentName);
            methodDelegate1 += teacher.getTeacherName; //可以指向不同类中的方法！
            //methodDelegate1 += teacher.getClassName; 指向签名不符的方法时提示错误！
            methodDelegate1.Invoke("张三");
            Console.ReadLine();
        }
    }

    class Student
    {
        private String name = "";
        public Student (String _name)
        {
            this.name = _name ;
        }
        public Student() {}
        public void getStudentName(String _name) 
        {
            if (this.name != "" )
                Console.WriteLine("Student‘s name is {0}", this.name);
            else
                Console.WriteLine("Student‘s name is {0}", _name);
        }
    }

    class Teacher
    {
        private String name;
        public Teacher(String _name)
        {
            this.name = _name;
        }
        public void getTeacherName(String _name)
        {
            if (this.name != "")
                Console.WriteLine("Teacher‘s name is {0}", this.name);
            else
                Console.WriteLine("Teacher‘s name is {0}", _name);
        }
        public string getClassName() 
        {
            return "Eanlish";
        }
    }
}

delegate double Operations(double x);

    class Program
    {
        static void Main()
        {
            Operations[] operations =
            {
               MathOperations.MultiplyByTwo,
               MathOperations.Square
            };

            for (int i = 0; i < operations.Length; i++)
            {
                Console.WriteLine("Using operations[{0}]:", i);
                DisplayNumber(operations[i], 2.0);
                DisplayNumber(operations[i], 7.94);
                Console.ReadLine();
            }
        }

        static void DisplayNumber(Operations action, double value)
        {
            double result = action(value);
            Console.WriteLine(
               "Input Value is {0}, result of operation is {1}", value, result);
        }
    }

    struct MathOperations
    {
        public static double MultiplyByTwo(double value)
        {
            return value * 2;
        }

        public static double Square(double value)
        {
            return value * value;
        }
    }